![](https://s4.51cto.com/images/blog/202103/04/2fddbd155c9880465ee071726787c196.png?x-oss-![](https://s4.51cto.com/images/blog/202103/04/06113c5d083f8e8ff9e5cf30c4f09e7d.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=)![](https://s4.51cto.com/images/blog/202103/04/3ad0bcee8ec711de9e66b52c2b02b7ab.png?x-oss-process=image/watermark,size_16,text_QDUxQ1RP5Y2a5a6i,color_FFFFFF,t_100,g_se,x_10,y_10,shadow_90,type_ZmFuZ3poZW5naGVpdGk=)
注意在循环对i+2不能直接写在for()中,试了几次发现这样得不出结果。